The electronics industry has experienced an ever-increasing demand for smaller and faster electronic devices which are simultaneously able to support a greater number of increasingly complex and sophisticated functions. Accordingly, there is a continuing trend in the semiconductor industry to manufacture low-cost, high-performance, and low-power integrated circuits (ICs). Thus far these goals have been achieved in large part by scaling down semiconductor IC dimensions (e.g., minimum feature size) and thereby improving production efficiency and lowering associated costs. However, such scaling has also introduced increased complexity to the semiconductor manufacturing process. Thus, the realization of continued advances in semiconductor ICs and devices calls for similar advances in semiconductor manufacturing processes and technology.
In particular, dimensional scaling has presented a challenge to the formation of metal contacts to source/drain features (e.g., such as a source/drain epitaxial layer) of a transistor. For example, during formation of metal contacts to separate, but adjacent, source/drain features, a dielectric layer may be formed to provide an isolation region between adjacent metal contact layers, and between a metal contact layer and an adjacent source/drain feature. However, in at least some conventional processes, an aggressively-scaled cut metal region, which is used to at least partially define a size of the dielectric layer, results in the dielectric layer being unable to provide adequate isolation. In some examples, and because of the scaled cut metal region, bridging (e.g., electrical shorting) may occur between a metal contact layer and an adjacent source/drain feature. In addition, the dielectric layer of the isolation region may suffer from time-dependent dielectric breakdown (TDDB) and thus fail to provide the desired isolation. In some cases, a hardmask used to keep adjacent metal contact layers separated may peel off during processing (e.g., during etching to provide the patterned dielectric layer for the isolation region), resulting in an electrical short between subsequently formed adjacent metal contact layers. Further, the material used for the dielectric layer may itself be more susceptible to having poor reliability (e.g., such as due to TDDB).
Thus, existing techniques have not proved entirely satisfactory in all respects.